Is there any way to trigger a piece of code on a warning generated by -w?

I have a piece of code that gets run intermittently, and every so often, it gets a warning about an uninitialized variable. Now, I could put some code that tests the variable that I *suspect* is bad before usage (this is a multiple hash dereference), but I don't know that I'd catch it, and I'd have to wait for the program to run again.

What I'd rather do is setup a code trap that would record the states of those variable in the subroutine, and a few others, using Data::Dumper or somesuch, to a file.

Consider the following fragment of code. We know that 3 parameters are being passed, since the @_ == 3 test passes, but without wrapping a test around each parameter, the perl diagnostics don't tell us *which* variable is the cause for the error messages. 
#!/usr/local/bin/perl -w

use strict;

{
   test ('arf', undef, 'dog');
}

sub test
{
   @_ == 3 or die "Incorrect number of arguments";

   my ($a, $b, $c) = @_;

   my %hash = ('arf' => {'spot' => {'dog' => 3}});

   print $hash {$a}->{$b}->{$c};
}

[download]
Anyone got any good ideas on this? Besides using tie() to every variable I might possibly reference... And why the perl interpeter couldn't print *what* variable is uninitialized?

--Chris

e-mail jcwren

In reply to Tying events to perl warnings and errors by jcwren

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